What would’ve happened if Blackbeard had captured Luffy in Water 7?

Hey everyone! I hope you’re enjoying our posts. And I hope you’ll enjoy this one too.
Blackbeard, as we know, captured Ace at Banaro Island. Ace was on a hunt for Blackbeard ever since we saw him at Alabasta. He finally found him at Banaro Island where, sadly, Ace was defeated and Blackbeard was given the title Of a Shichibukai. As Blackbeard mentioned to Ace, his plan was to originally capture Luffy at Water 7 and then later hand him to the marines. Ace, knowing this, knew he couldn’t step out of the battle anymore. Not that I’m saying he would.
Let’s assume that Blackbeard would’ve met Luffy at Water 7. Luffy would’ve been ultimately defeated since he was in no condition to battle. Even if he was, he would’ve been bitterly defeated. Now Luffy would’ve been in place of Ace. Assuming that the execution would take place at Marineford, I’m guessing 3 important people would turn up to rescue him, along with the Strawhat Pirates who were too weak to rescue anyone from the Marines at full force.
The first would’ve been the Whitebeard Pirates, led by Whitebeard himself. Luffy’s crew would’ve definitely tried to save Ace, had they been given a chance. I don’t think it’s wrong to assume that Ace’s crew would do the same. We know that the Whitebeard Pirates were not enough to stop the Execution. But we’re just getting started.
Onwards to Yonkou, ‘Akagami’ Shanks. Shanks would 100% turn up at Marineford. Luffy was entrusted with Roger’s will by Shanks. To protect Roger’s will and to protect someone who’s dear to him, Shanks would wreak havoc at Marineford.
Now the tide seems to turn towards the Pirates’ favour. But hold on to your horses. We’re not done yet.